Transcript X-Ray Technology

X-Ray
Technology
By:
PROF. Dr. Moustafa Moustafa Mohamed
Outcomes:
By the end of the course the student will learn:
1-Introduction to Medical Imaging .
2-Exactly what is an X – Ray?
3-Types and uses of X-ray.
4-Various uses of the X – Ray.
5-Production of X-rays.
Production of X-rays (1)
• X-rays are produced when rapidly moving electrons that have
been accelerated through a potential difference of order 1 kV
to 1 MV strikes a metal target.
Evacuated
glass tube
Target
Filament
Production of X-rays (2)
• Electrons from a hot element are accelerated onto a
target anode.
• When the electrons are suddenly decelerated on
impact, some of the kinetic energy is converted into
EM energy, as X-rays.
• Less than 1 % of the energy supplied is converted
into X-radiation during this process. The rest is
converted into the internal energy of the target.
Properties of X-rays
• X-rays travel in straight lines.
• X-rays cannot be deflected by electric field or
magnetic field.
• X-rays have a high penetrating power.
• Photographic film is blackened by X-rays.
• Fluorescent materials glow when X-rays are
directed at them.
• Photoelectric emission can be produced by X-rays.
• Ionization of a gas results when an X-ray beam is
passed through it.
X-ray Spectra (1)
• Using crystal as a wavelength selector, the intensity of
different wavelengths of X-rays can be measured.
X-ray Spectra (2)
• The graph shows the following features.
– A continuous background of X-radiation in which the
intensity varies smoothly with wavelength. The
background intensity reaches a maximum value as the
wavelength increases, then the intensity falls at greater
wavelengths.
– Minimum wavelength which depends on the tube voltage.
The higher the voltage the smaller the value of the
minimum wavelength.
– Sharp peaks of intensity occur at wavelengths unaffected
by change of tube voltage.
Minimum wavelength in the X-ray Spectra
• When an electron hits the target its entire kinetic
energy is converted into a photon.
• The work done on each electron when it is
accelerated onto the anode is eV.
• Hence hf = eV and the maximum frequency
f max
eV

h
Therefore,
min
hc

eV
Continuous (Bremsstrahlung) X-Ray
Production
Recommended text books
Medical Physics
Experiments in Modern physics
Advanced level physics
Applied physics
College physic
Physics for Scientists and engineers